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(No Model.)

G. M. FARRAR.

CHECK FOR OIL WELL TUBES.

o. 244,042. Patented July 12, 1881,.

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UNITED STATES PATENT OFFICE.

OHILION M. FARRAR, OF BUFFALO, NEW YORK.

CHECK FOR OIL-WELL TUBES.

SPECIFICATION forming part of Letters Patent No. 244,042, dated July 12, 1881.

Application filed March 14, 1881. (No model.)

To all whom it may concern:

Be it known that I, CHILION M. FARRAR, a citizen of the United States, residing in the city of Butt'alo, in the county of Erie and State of New York, have invented certain new and useful Improvements in Checks for Oil-Well Tubes, of which the following is a specification.

Heretot'ore checks for oil-well tubes have been made in the form of a thin metal disk having an equal strength for resisting pressure on either side. The objection to such plates is that when strong enough to resist the required pressure on one side they are too strong to be easily broken on the opposite side.

The object of my invention is to avoid this objection by adapting an oil-check to resist great pressure on one side, and to be easily broken away,when necessary, by amuch lighter pressure on the other side; and it consists of a check-plate made convex on one side and having a strong rim projecting up from the other side, adapted to screw onto the end of the tube, the convex portion being thinner where it joins the rim, as and for purposes which will be more clearly hereinafter shown by reference to the accompanying drawings, in which Figure 1 is a vertical central section through the oil-check and a piece of oil-well tube. Fig.2 is a side elevation ofa small piece of tube and a portion of a check-plate attached thereto, and Fig. 3 represents a plan showing the convex face of the check-plate.

A represents a piece of ordinary oil-well tube, provided with the usualscrew portion, a.

Bis the checleplate rim adapted to screw onto the tube A.

0 represents the thicker part of the convex portion, and D the thinner part.

The check is constructed of some metal capable of bearing a strong crushing strain and of being easily broken by either a tensile or transverse strain. 1 use zinc as being a suitable metal for the purpose, although there are other metals or combinations of metals that may be used.

It is well known that in tubing a flowing well the oil and gas will often flow up with great force through the tube as it is being let down, to the great inconvenience of the workmen.

In operating with my invention the checkplate is screwed onto the end of the tube, as shown in Fig. 1, and the tube, after being provided with the usual packing, is let down into the well, and' when in place the convex portion 0 is broken off, as shown in Fig. 2, by a light blow on the inside from an iron bar or its equivalent, which is let down into the tube in any well-known way, thereby leaving an opening for the oil to fiow up.

It will now be seen that the construction and form of the check is such that a great pressure may be applied against the convex portion without breaking it, and that a much less force will be required to break it from the opposite side.

If desired, the check may be made small enough to slip into the end of the tube against a shoulder or flange on the inside, so that when another piece of tube is screwed on the check will be held in place between the two.

I claim as my invention- 1. A check for oil-well tubes, consisting of a convex portion, 0, thin portion D, and a rim, B, adapted to screw onto the tube, as and for the purposes specified.

2. A check for oilwell tubes, the lower portion of which is provided with a rounded or convex surface, said convex surface being thinner where it joins the rim, substantially as and for the purposes described.

OHILION M. FARRAR.

Witnesses:

JAMES SANGSTER, A. J. SANGSTER. 

